1. Field of the Invention
The invention pertains to the field of chain tensioners. More particularly, the invention pertains to a blade tensioner with a distal end for damped wedging interaction with a complementary stationary block.
2. Description of Related Art
Blade tensioners are well-known in the prior art. A blade-type tensioner is used to impart tension on a chain. A blade tensioner generally includes a plastic blade shoe with an arcuately curved chain-sliding face, a plurality of leaf spring-shaped blade springs provided opposite the chain-sliding face, and a metal base that swingably supports a proximal end portion of the blade shoe and slidably supports a distal end portion of the blade shoe. During operation, a chain slides and travels along the chain-sliding surface of the blade shoe and a resilient force due to the elastic deformation of the blade shoe and the blade spring is applied to the chain by the blade shoe and proper chain tension is maintained. Different types of slidable supports for the distal end have been used in blade tensioners, but they do not dampen chain vibrations sufficiently during chain tensioning.
A wedging effect has been used in mechanical and hydraulic tensioners to dampen chain vibrations. In U.S. Pat. No. 4,291,416, “CHAIN TENSIONER”, issued to Hoeptner III on Sep. 22, 1981, the mechanical chain tensioner has a wedgable means co-acting with a plunger to block its retraction. In U.S. Pat. No. 5,951,423, “MECHANICAL FRICTION TENSIONER”, issued to Simpson on Sep. 14, 1999, the mechanical tensioner has a wedge-shaped plunger, and wedge-shaped blocks are pushed toward the plunger by springs to provide damping. In U.S. Pat. No. 6,361,459, “TENSIONER”, issued to Serkh et al. on Mar. 26, 2002, the mechanical belt tensioner dampens based on the sliding action of mutually-opposed wedges. In U.S. Pat. No. 6,767,302, “HYDRAULIC TENSIONER”, issued to Seungpyo on Jul. 27, 2004, the hydraulic tensioner uses a wedging effect to prevent the plunger from moving backwards. In U.S. Publication No. 2002/0094894, “TENSIONER FOR A CHAIN OR BELT”, by Poiret et al., the hydraulic tensioner uses wedging to inhibit further inward movement of the plunger during tensioning. In U.S. Publication No. 2003/0186764, “CHAIN TENSIONER”, by Yoshida et al., the hydraulic tensioner has a pair of wedge-shaped cams received in tapered recesses.
Mechanical and hydraulic tensioners are considerably more expensive and complicated than blade tensioners, and there are numerous applications, in which a blade tensioner is preferably used. There is a need in the art for a blade tensioner with better damping of chain vibrations during chain tensioning.